The present invention relates to a sheet feeding device for an image forming apparatus which is used to feed a transfer sheet to a transfer region, and more particularly relates to a pair of conveyance rollers disposed in a conveyance passage of the sheet feeding device.
In an image forming apparatus, a relatively simple sheet feeding device is adopted which is operated in the following manner: before a transfer sheet sent out from a sheet feeding cassette is conveyed to a transfer region, it is brought into contact with a shutter member which blocks a conveyance passage and stops the sheet; the shutter member is withdrawn synchronously with the movement of a toner image formed on an image forming body; and then the transfer sheet is conveyed again.
In the simple sheet feeding device, a drive roller which is always rotated and an idle roller which comes into pressure contact with the drive roller, are adopted as a pair of conveyance rollers, and when a transfer sheet is stopped by the shutter member, the drive roller slips on the transfer sheet, so that an idling condition can be maintained.
However, the drive roller is a solid rubber roller, and the idle roller is a resin roller or a solid rubber roller. Therefore, while the drive roller is slipping on the transfer sheet, the transfer sheet is vibrated due to the friction between the drive roller and the transfer sheet, so that unpleasant noise is generated.
In order to prevent this unpleasant noise, it is effective to lower the pressing force of the idle roller against the drive roller. On the other hand, when the pressing force is lowered, the conveyance force of the transfer sheet is also lowered, so that there is a possibility that the transfer sheet can not be conveyed appropriately.
The present invention has solved the aforementioned problems, and it is a primary object of the present invention to provide a sheet feeding device for an image forming apparatus in which abnormal sound caused when a transfer sheet is vibrated during slippage, can be prevented without reducing the conveyance force.